This specification describes the use of directional loudspeakers in vehicle passenger compartments. One popular type of directional loudspeaker is a directional acoustic array. Information on directional acoustic arrays can be found in Harry F. Olson, “Gradient Loudspeakers,” J. of the Audio Engineering Society, March 1973, Volume 21, Number 2, in U.S. Pat. No. 5,870,484, and in U.S. Pat. No. 5,809,153.